Prevent ServletComponentScan to run again with AOT

Closes gh-34563

Author: snicoll

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/ServletComponentScanRegistrar.java

@@ -22,9 +22,11 @@
 import java.util.Set;
 import java.util.function.Supplier;
 
+import org.springframework.beans.factory.aot.BeanRegistrationExcludeFilter;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.GenericBeanDefinition;
+import org.springframework.beans.factory.support.RegisteredBean;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.type.AnnotationMetadata;
@@ -100,4 +102,13 @@ private void addPackageNames(Collection<String> additionalPackageNames) {
 
 	}
 
+	static class ServletComponentScanBeanRegistrationExcludeFilter implements BeanRegistrationExcludeFilter {
+
+		@Override
+		public boolean isExcludedFromAotProcessing(RegisteredBean registeredBean) {
+			return BEAN_NAME.equals(registeredBean.getBeanName());
+		}
+
+	}
+
 }

spring-boot-project/spring-boot/src/main/resources/META-INF/spring/aot.factories

@@ -20,3 +20,6 @@ org.springframework.boot.jackson.JsonComponentModule.JsonComponentBeanFactoryIni
 org.springframework.beans.factory.aot.BeanRegistrationAotProcessor=\
 org.springframework.boot.context.properties.ConfigurationPropertiesBeanRegistrationAotProcessor,\
 org.springframework.boot.jackson.JsonMixinModuleEntriesBeanRegistrationAotProcessor
+
+org.springframework.beans.factory.aot.BeanRegistrationExcludeFilter=\
+org.springframework.boot.web.servlet.ServletComponentScanRegistrar.ServletComponentScanBeanRegistrationExcludeFilter

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/servlet/ServletComponentScanRegistrarTests.java

@@ -16,13 +16,22 @@
 
 package org.springframework.boot.web.servlet;
 
+import java.util.function.Consumer;
+
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.aot.test.generate.TestGenerationContext;
 import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.aot.ApplicationContextAotGenerator;
+import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.annotation.AnnotationConfigurationException;
+import org.springframework.core.test.tools.CompileWithForkedClassLoader;
+import org.springframework.core.test.tools.TestCompiler;
+import org.springframework.javapoet.ClassName;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -121,6 +130,32 @@ void basePackageAndNoBasePackageAreCombinedCorrectly() {
 				"com.example.foo", "com.example.bar");
 	}
 
+	@Test
+	@CompileWithForkedClassLoader
+	void processAheadOfTimeDoesNotRegisterServletComponentRegisteringPostProcessor() {
+		GenericApplicationContext context = new AnnotationConfigApplicationContext();
+		context.registerBean(BasePackages.class);
+		compile(context, (freshContext) -> {
+			freshContext.refresh();
+			assertThat(freshContext.getBeansOfType(ServletComponentRegisteringPostProcessor.class)).isEmpty();
+		});
+	}
+
+	@SuppressWarnings("unchecked")
+	private void compile(GenericApplicationContext context, Consumer<GenericApplicationContext> freshContext) {
+		TestGenerationContext generationContext = new TestGenerationContext(
+				ClassName.get(getClass().getPackageName(), "TestTarget"));
+		ClassName className = new ApplicationContextAotGenerator().processAheadOfTime(context, generationContext);
+		generationContext.writeGeneratedContent();
+		TestCompiler.forSystem().with(generationContext).compile((compiled) -> {
+			GenericApplicationContext freshApplicationContext = new GenericApplicationContext();
+			ApplicationContextInitializer<GenericApplicationContext> initializer = compiled
+				.getInstance(ApplicationContextInitializer.class, className.toString());
+			initializer.initialize(freshApplicationContext);
+			freshContext.accept(freshApplicationContext);
+		});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@ServletComponentScan({ "com.example.foo", "com.example.bar" })
 	static class ValuePackages {